The entire GUI for the Minecraft Vanilla Server software is completely broken, you can type commands into the console, and you view the players in game, but you cannot right click on player names, there are no words that show up in the right-hand box of the GUI, and you can not see any of the RAM usage in the top-left box of the GUI.
This needs to be fixed now.
Thank you for your report.
However, your ticket has been resolved as a duplicate.
This issue has been linked to the original bugreport: MC-32850. You can find or add further information on that report.
Please search before reporting any bugs, as it's likely that one exists already.